A number of systems have been developed for winding strand into a cylindrical package and subsequently encasing the wound package in a membrane to protect the strand and to facilitate withdrawal of the strand from the package.
A number of such systems included thermally shrinking a plastic or polymeric membrane over the outer surface of the wound body of the strand. Although such systems did improve the run-out capabilities of the package, a tendency for the outermost layer of the strand to collapse in a ball or "bird's nest" still existed. That is, as a strand was withdrawn from the package working from the inside diameter of the package to the outer diameter of the package, the outermost layers exhibited a tendency to collapse and tangle and, thus, preclude continuous operation and complete utilization of the strand.
Other systems incorpoated an adhesive between the membrane and the outer layer of strand to retain the strand against the membrane wall. In a number of instances, the adhesive contaminated the strand, among other problems.
Another system disclosed in U.S. Pat. No. 4,220,295 incorporated an elastic membrane wound about the cylindrical portion of the package of strand, wherein the membrane is wound to a thickness and is stretched sufficiently to partially collapse when the strand is withdrawn from the package, such that the membrane mechanically captures the outer layer of strand of the body of strand.
Such a system works well in many instances; however, in some situations, primarily when the withdrawal speed of the strand is very high, the package can collapse with extreme non-uniformity due to the dynamic forces generated by a rapidly whiping strand. Also, there is a tendency of the strand, when being withdrawn at high speed to loop over the exterior of empty packages and snare such package when the empty packages are not removed from a creel-type operation, thus interrupting the pay out of strand.
The present invention comprises a modification to the system disclosed in U.S. Pat. No. 4,220,295.